Green Synthesis of 4-aryl-3,4-Dihydrochromeno[3,4-e][1,3]Oxazine-2,5-Dione in Aqueous Media by Condensation of 4-Hydroxycoumarin with Aromatic Aldehydes and Methyl Carbamate

Abstract

A green and efficient synthesis of the title compounds has been achieved in a one-pot, three-component reaction of 4-hydroxycoumarin and aromatic aldehydes with methyl carbamate catalysed by p-toluenesulfonic acid in aqueous media to afford 4-aryl-3,4-dihydrochromeno[3,4-e][1,3]oxazine-2,5-diones in excellent yields. The salient features of this protocol are: short reaction times, high yields and absence of any hazardous organic solvent. Consequently, this procedure could be classified as green chemistry.